DLAs Probing Quasar Host Galaxies Hayley Finley P. Petitjean, P. Noterdaeme, I. Pâris + SDSS III BOSS Collaboration 2013 A&A 558 111
Outline Feedback mechanisms in QSO host galaxies Strong DLAs at zqso act as coronagraphs Detect narrow Lyα emission from QSO host galaxies Compare associated absorbers that reveal narrow Lyα emission with those that do not Characterize the narrow Lyα emission Follow-up projects to investigate Narrow Line Region / extended emission
Feedback in Ordinary Galaxies IGM Galaxy : - IGM accretes onto Galaxy - Star formation increases Galaxy IGM : - Galactic winds enrich IGM
Feedback in Ordinary Galaxies IGM Galaxy : - IGM accretes onto Galaxy - Star formation increases BG QSO Galaxy IGM : - Galactic winds enrich IGM
Lyα Emission in an Intervening DLA Detect emission from intervening absorber Likely a starburst galaxy Galactic winds Noterdaeme et al. 2012 J113520.39 001053.56 z = 2.207 b 0.1 (0.9 kpc proper) (SFR) 25 M yr 1 from Hα
Feedback in Intervening Galaxies IGM Galaxy : - IGM accretes onto Galaxy - Star formation increases Galaxy IGM : - Galactic winds enrich IGM BG QSO?
Feedback from Quasar Host Galaxies Add energy to galactic environment: Kinematics Winds blow gas out of galaxy Ionizing flux Primary source of UV ionization What is the relationship between gas accretion, star formation, and energy input
Lyα Emission in zabs zqso DLAs Previous Detections : J124020.91+145535.6 Hennawi et al. 2009 B 0405 331 Ellison et al. 2002 PHL 1222 Møller et al. 1998 Q 2059 360 Pettini et al. 1995 PKS 0528 250 Møller & Warren 1993 Hennawi et al. 2009 Ruled out absorber as source Emission intrinsic to quasar host
Spectrum Dominated by BLR Emission Galaxy Broad Lyα + N V NLR Broad Si IV Broad C IV BLR 1 pc Narrow Lyα emission blended with broad component
Associated DLA reveals NLR Emission Gas cloud creates a DLA at zqso DLA blocks broad Lyα emission NLR Galaxy Narrow Lyα Broad C IV BLR 1 pc DLA DLA Narrow Lyα emission superimposed on DLA trough Lyα emission is only from the
A Second Type of Associated DLA Nearby galaxy acts as a screen Both BLR, NLR blocked N V NLR BLR 1 pc Galaxy Si IV C IV DLA DLA
What gives rise to the DLA? DLA Dense, compact gas cloud associated with the quasar host galaxy? Neighboring Galaxy DLA
What gives rise to the DLA? DLA Study properties of a complete sample of quasar spectra with zdla zqso absorptions Expect gas clouds & galaxies to have different DLA from properties. gas cloud? DLA from neighboring galaxy? DLA
Need many sight lines to find occurrences SDSS-III BOSS: Baryon Oscillation Spectroscopic Survey Survey Properties: 2009-2014 160,000 quasars at <z> = 2.5 87, 822 in DR9 catalog Spectra Properties: 3600 Å λ 10000 Å Resolution 2000 Visual inspection of arriving data
Gathering a Sample of Associated DLAs Search DR9 Selection Criteria: DLA Catalog log N(HI) 21.2 (Noterdaeme et al. 2012) zdla zqso 3000km/s No BAL Get system redshift from metals Re-mesure DLA column densities
Defining the Complete Sample Complete log N(HI) 21.3 zdla zqso 1500km/s
Anticipated No of Intervening DLAs at zqso Calculate total absorption path (Δχ) for DR9 QSOs Criteria : Non-BAL QSOs 2.0 zqso 3.5 Δv 1500 km/s log N(HI) 21.3 Use N(HI) distribution function to estimate fraction of absorption paths with a log N(HI) 21.3 DLA Expect 13 DLAs, but observe 31 Clustering around quasars accounts for overdensity
Sample Characteristics Compare DLAs with and without narrow Lyα emission : Velocity Differences (DLA w.r.t. QSO) Metal absorption equivalent widths Colors (r-i, r-z) Reddening: E(B-V) Estimate depletion Consistently lower W0, FeII to W0, CII ratio for DLAs with narrow Lyα emission Dustier?
Sample Characteristics ompare DLAs with and without narrow Lyα emission : Velocity Differences (DLA w.r.t. QSO) Metal absorption equivalent widths Colors (r-i, r-z) Reddening: E(B-V) No clear differences. Estimate depletion Consistently lower W0, FeII to W0, CII ratio for DLAs with narrow Lyα emission Dustier?
Associated DLAs with Emission 26 DLAs reveal narrow Lyα emission Combined spectrum from 11 DLAs with strong Lyα emission Emission is symmetric: No HI in front of emitting region
Lyα Emission Peak Comparison Finley et al. 2013 Associated DLAs Jones et al. 2012 Lyman Break Galaxies Redshifted emission peak Blueshifted absorption trough Symmetric profile Emitting region relatively void of HI gas Asymmetric profile Emitting region surrounded by HI gas Absorbing gas is separate from emitting region
Lyα Emission Luminosity Lyman-Alpha Emitters: Star-formation Anticipate lower luminosities than QSO host Lyman-Alpha Emitters QSO Host Galaxies Radio Galaxies Radio Galaxies: AGN, jets Anticipate higher luminosities than QSO host QSO host galaxies: 50% similar to LAE 50% similar to radio galaxies DLA is likely a gas cloud
What can we say about the absorbers? DLAs properties not distinct for neighboring galaxies and gas clouds Detect narrow Lyα emission Absorber must be small compared to emitting region Absorber size < 1 kpc : DLA blocks significant portion of Lyα emission Luminosities comparable to Lyman-Alpha Emitters Large cloud or small galaxy? Absorber size < 10 pc : Detect strong Lyα emission Luminosities approach those of Radio Galaxies
Follow-Up Projects Detect extended Lyα emission by taking spectra at different position angles Magellan Telescope/MagE data obtained Slit oriented Slit oriented North-South East-West Observe other NLR emission lines to determine how the absorbing gas is related to the host galaxy VLT/X-Shooter Classed B S
Conclusions Unprecedented sample New technique for studying quasar host galaxies Observe narrow Lyα emission when absorber is small compared to the emitting region 75 % Absorber completely blocks host galaxy emission 12.5 % Lyα luminosities comparable to LAEs : emission partially obscured 12.5 % Lyα luminosities comparable to radio galaxies : emission largely unobscured compact absorber (HI cloud in host galaxy) Follow-up projects to explore the relationship between absorbing gas and NLR emission